Arc chute for circuit breakers



March 1962 c. J. YARRICK 3,025,376

ARC CHUTE FOR CIRCUIT BREAKERS Filed May 15, 1958 2 Sheets-Sheet 1 EULBY I 4,4

March 13, 1962 c. J. YA RRICK 3,025,376

ARC CHUTE FOR CIRCUIT BREAKERS Filed May 15, 1958 2 Sheets-$heet 2 JIZE.5.

United States Patent ()fiice 3,025,376 Patented Mar. 13, 1962 3,025,376ARC CHU'IE FOR CIRCUIT BREAKERS Charles J. Yarrick, Haddoniield, N.J.,assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., acorporation of Pennsylvania Filed May 13, 1958, Ser. No. 735,041 9Claims. (Cl. 200-144) My invention relates to an arc chute forair-immersed circuit breakers, and more particularly is directed to adual-flow arc chute having a gas mixing chamber and elongated gasdischarge paths for discharging gases caused during arc conditions fromthe chamber.

Specifically, my invention is an improvement over the arc chutedescribed in my copending application Serial No. 647,095, filed March19, 1957, and entitled Arc Chute Design for Circuit Breakers. In myabove noted copending application I provide an arc chute structure inwhich ionized gas created during arcing conditions is conducted overalternative paths to a mixing chamber and is mixed by impartingsubstantial turbulence to the gas Within the chamber so as to causerapid cooling and deionizing thereof. The gas, after being sode-ionized, may then be safely discharged from the arc chute confineswithout the prior existing danger of a phase-to-ground fiashov-erthrough the ionized gas to structures external of the circuit breaker atground potential.

The turbulence achieved in the above noted system was forced by battlingmeans which was positioned within the mixing chamber and interposedbetween various points of gas entrance to the chamber from the arcingspace. The turbulence is desirable, since a greater amount of gas willthereby come into contact with the relatively cool surface of thechamber so as to be cooled thereby. Hence, by cooling the gas, thedegree of ionization of the gas is decreased and may be safelydischarged from the chamber.

However, since substantial baffling is required in this type of system,a back pressure is built up which prevents a rapid scavenging of gasfrom the arcing area. Because of this, a sufiicient amount of ionizedgas may be left within the arcing area after extinguishing the are sothat an arc restrike is possible.

The essence of my present invention is to provide a relativelyunrestricted path from the arcing space to the exterior of the arc chutewhile still achieving substantial de-ionization of the gas throughmixing thereof and cooling. To this end, I provide a plurality ofserpentine paths for conducting the gas from a mixing chamber which issubstantially free of bathing means to the exterior of the arc chute.Since the path is serpentine, which is meant here to be a path ofrelatively long distance when compared to the distance between thebeginning and end of the path, the gas is moved over relatively longareas of cooling surface. Thus, it is possible to cool the gas in a muchmore efficient manner than is possible when the baffling structure isused, as in my copending application.

Furthermore, the serpentine paths, while providing a relatively largecooling area for the gas, provide a relatively small resistance to thegas movement. Accordingly, the back pressure on the gas will be low sothat extremely rapid scavenging of the area adjacent the cooperatingcontacts is achieved, and the danger of restriking an arc issubstantially lessened.

Thus, the primary object of my invention is to provide a circuit breakerare chute having a novel deionizing means.

Another object of my invention is to provide a novel arc chute for acircuit breaker in which the ionized gas generated during arcingconditions is rapidly de-ionized and discharged into the external spaceat such a rapid rate that a restrike of an are due to the presence ofionized gas in the arcing chamber is prevented.

Another object of my invention is to provide a novel are chute for anair-immersed circuit breaker wherein ionized gas is conducted to amixing chamber over a plurality of paths, and is thereafter rapidlyde-ionized and discharged to the external space over one or moreserpentine paths, thus exposing a relatively large cooling area to thegas being discharged.

These and other objects of my novel invention will become apparent fromthe following description when taken in connection with the drawings, inwhich:

FIGURE 1 is a side view of a typical air circuit breaker adapted withthe arc chute of my novel invention.

FIGURE 2 is an exploded perspective view of the arc chute illustrated inFIGURE 1 and presents clearly the details of my invention.

FIGURE 3 is a partial side cross-sectional view of FIG- URE 2.

In FIGURE 1, I have illustrated a side view of one pole of a circuitbreaker in which my instant invention can be used. However, it will beapparent to those skilled in the art that my novel are chute could beused on any number of circuit breakers and is not limited to thestructure shown in FIGURE 1. Furthermore, I have only illustrated asingle pole of a circuit breaker although it will be apparent that thebreaker represents only one pole of a three pole breaker. Furthermore,since the particular circuit breaker forms no part of my instantinvention, the details of the operating and trip mechanism are notdescribed in detail herein since a thorough description thereof can befound by reference to my copending application, Serial No. 647,095 filedMarch 19, 1957 entitled Arc Chute Design for Circuit Breakers andassigned to the assignee of the instant invention.

The novelty of my instant invention is contained within the arcextinguisher or arc chute which is usually contained within a circuitbreaker, such as that illustrated in FIGURE 1, having stationary maincontact 17, a movable main contact 16, a stationary arcing contact 19and a movable arcing contact 20. The movable arcing contact 20 iscontained on the contact arm 40 and the main movable contact iscontained on the movable arm 39.

The entire circuit breaker is positioned within a housing 60 having afront door 41 and a metal back base 48. The circuit breaker isautomatically and manually operated through the operating mechanism 42and is provided with an escutcheon assembly 43 to which the manualoperating handle 46 can open and close the breaker. The solenoidassembly 44 contains a closing coil 45 which when energized willautomatically close the breaker through the operating mechanism 42. Thebreaker can be automatically tripped by means of the dual overcurrentdevice 47. The dual overcurrent device 47 is operative to simultaneouslytrip all poles of the breaker through the common tripper bar 50.

The circuit breaker is energized through the main separable contacts 59to which the current studs 51 are connected. A common opening spring 52is utilized to provide the opening force through the contact arm path 53to simultaneously open all three poles of the breaker when it is eitherautomatically tripped by means of the dual overcurrent device 47 ormanual operating device 46. The arc chute assembly is maintained in thecircuit breaker by means of the support clamp 13 and the screw 15 Adetailed representation of the novel are chute 10 is seen in the partialperspective view of FIGURE 2.

desirable means as, for example, by being positioned within slotscontained within the side of the insulated housing 22. The are plates 23are preferably made of iron so as to provide a magnetic assist once thearc is drawn between the cooperating contacts 19, 20, In addition, thearc plates 23 are preferably provided with a center slot such as 24which is above and adjacent to the cooperating contacts 19, 20.

The stationary arcing contact 20 is provided with a back are runner 25,and a front are runner 26 in the well known manner.

As seen in FIGURE 2, the back are runner 25 forms one wall of a chamberhaving its other wall defined by the last or most rearward arc plate ofarc plates 23 and the chamber communicates between the arcing area and amixing chamber 29 positioned above baffie plate 28 which lies across thetop of the arc plates 23.

In a similar manner, the front are runner 26 defines a wall of acommunicating chamber from the arcing area to the upper mixing chamber29 whose other wall is defined by the first or most forward arc plate ofarc plates 23.

Within chamber 29, and as best seen in FIGURE 3, additional bathingmeans such as baffle 30 having relatively large openings therein may beprovided to impart a degree of turbulence to gas entering chamber 29.Note further that gas can enter chamber 29 from either of the chambersdefined by are runners 25 or 26 as Well as gas which rises upwardly andthrough the baffle 28.

The chamber 29 communicates with areas external to housing 22 through aplurality of serpentine paths so that the gas is exposed to a relativelylarge cooling area. Two of these paths 31 and 32 are formed within themolded housing and are curved in shape, as shown in FIGURES 2 and 3, sothat gas within the chamber 29 will flow over molded sections such assections 33 and 34 along the paths 31 and 32 until they reach the end ofcover members 35 or 36 respectively to be discharged into the areaexternal of the housing 22. This path is clearly shown in FIGURE 2 forthe case of serpentine path 31 by the arrow which indicate the flow ofgas created by the disengagement of contacts 19 and 29.

Alternative serpentine paths are similarly provided by means of themember 37 positioned at the top of chamber 29 and spaced from eitherside wall, as best seen in FIGURE 3. Member 37 will force gas in chamber29 to flow outwardly toward the sides and around it until the gasreaches openings, such as openings 38a and 38b in upper portion 39 ofthe molded housing. The gas then is sidewardly directed again by thehood portions 39a and 39b and directed to an area external of the arcchute.

The arrows in the upper serpentine path of FIGURE 2 indicate the mannerin which ionized gas will have to flow for the case of the right-handportion of the breaker of FIGURE 3. Clearly, the gas must come intocontact with a relatively large cooling area which includes two halvesof the surface of barrier 37, the lower half of the surface of member3%, the upper half of the surface of member 3%, and the under surface ofhood 39a.

If desired, members 37, 39 and 39a may be integral components of amolded housing, However, they could be individual members secured in thepositions shown, in any desired manner.

FIGURE 1 illustrates the condition of the cooperating contacts when thebreaker is in the closed position and carrying normal load current. Atthis time, the current will flow from the main upper separable contactassembly 59 through the current stud 51 and out through the lower mainseparable contact assembly 59. When the contacts separate, as forexample on the occurrence of an overload current condition resulting inthe operation of the dual overload trip device 47, the main contacts 16,17 will initially disengage while the arcing contacts 19, 20 remainengaged. Thus, all of the current will initially flow through thecooperating arcing contacts 19, 20. Subsequently, the arcing contacts19, 20 are separated, thereby drawing an arc therebetween.

The system is designed so that the arc will rise into the arc chute.That is, the arc itself will tend to rise with the hot gases createdthereby and also will be forced into the arc chute due to the magneticforces created from the magnetic field of the arc in the magnetic plates23 of the arc chute. The ends of the arc will move upward on both theback and front are runners 25, 26 and the arc plates 23 will beeffective in extinguishing the arc. The are chute is designed so thatthe arc will not exist above the top of the arc plates 23. That is, thebaffle 28 will relieve the high pressure hot gases from the chamberwhich contains the arc plates, and will prevent the are from passingtherethrough.

However, the gases passing through the openings in the baffle plate 28have a large degree of ionization, and in the absence of applicantsnovel cooling and deionizing system, these hot gases would be vented outof the arc chute area and could possibly create a conductive path froman energized component of the circuit breaker to the grounded housing 60of the breaker, thereby resulting in a phase-to-ground fault.

However, with the novel construction of my are extinguisher, I haveprovided a plurality of paths by which the gases can move into themixing chamber 29. Thus, some of the gases will travel up the chambersdefined by are runners 25 and 26 to enter the mixing chamber withconsiderable velocity. These gases will mix with the other ionized gaseswhich have reached the mixing chamber 29 through the usual means, suchas the spaces adjacent the arc plates and through the openings in baffle28. The impingement of the high velocity gases entering the mixingchamber 29 with those entering the mixing chamber through the baffle 28will result in a high degree of turbulence which is emphasized by theadditional bafiles, such as baflle 30 of FIGURES 2 and 3, which arepositioned in the chamber,

As is well known in the circuit interruption art, the mere increase inturbulence will in itself result in a larger degree of de-ionization ofthe gases within the chamber by increasing the possibility ofrecombination of positive ions and free electrons.

Further, the increased turbulence of the hot gases will cause them tocome into contact with a larger surface in the mixing chamber to therebysubstantially increase the cooling effect or de-ionization of the gases.That is, since the molecular velocity increases with the square of thetemperature, at high temperatures the molecular velocity is high enoughto cause ionization and thus make the gas conductive. By cooling thegas, it is apparent that the ionization process will be impeded and thegases rendered less conductive.

This effect is further emphasized in the instant invention by forcingthe gases, after leaving chamber 29, to travel a tortuous serpentinepath which will expose them to a relatively large cooling area so thatupon their discharge into the external atmosphere, the degree ofionization will be relatively small and the danger of a phaseto-groundfault will be substantially eliminated.

Furthermore, since the gases travel over a relatively unimpeded path,the back pressure on the gas will be substantially negligible so thationized gas in the area of the cooperating contacts may be rapidlyscavenged from the area to thereby quickly re-establish a highdielectric in that area because of the replacement of the hot ionizedgases by cool tin-ionized air.

Although I have described preferred embodiments of my novel invention,many variations and modifications will now be obvious to those skilledin the art, and I prefer therefore to be limited not by the specificdisclosure herein but only by the appended claims.

I claim:

1. An arc extinguisher comprising an insulating hous- ,ing and aplurality of arc plates; said plurality of arc plates supported withinsaid housing and being positioned in spaced relation with each otheralong a line extending between ends of said housing; each of saidplurality of arc plates having a center slot and being positioned aboveand adjacent cooperable contacts of a circuit breaker; said insulatinghousing containing a mixing chamber immediately above said plurality ofarc plates; a passage within said housing and located at one end thereofcommunicating at one end with said cooperable contacts and the other endwith said mixing chamber; said passage being adapted to guidesubstantially greater quantities of gas into said mixing chamber thaneach of the spaces between adjacent arc plates, a discharge passageleading from said mixing chamber to an area external of said insulatinghousing at a side thereof; said passage having a length substantiallylonger than the distance between its input end at said mixing chamberand its output end externally of said insulating housing.

2. An arc extinguisher comprising an insulating housing and a pluralityof arc plates positioned within said housing in spaced relation witheach other along a line extending between ends of said housing; saidplurality of plates having a center slot and being positioned above andadjacent to cooperable contacts of a circuit interrupter; a batiie plateimmediately above said plurality of arc plates and extending in adirection perpendicular thereto; said insulating housing containing amixing chamber above said arc plates and being partially defined by saidbattle; a passage within and at one end of said housing extending fromsaid cooperable contacts directly to said mixing chamber; said passagebeing adapted to guide substantially greater quantities of gas into saidmixing chamber than each of the spaces between adjacent arc plates, saidpassage by-passing said bafi'ie plate and being defined on one side byan end are plate and on the other side by said insulating housing; adischarge passage leading from said mixing chamber to an area externalof said insulating housing at a side thereof, said passage having alength substantially longer than the distance between its input end atsaid mixing chamber and its output end externally of said insulatinghousing.

3. An arc extinguisher comprising an insulating housing and a pluralityof arc plates positioned within said housing in spaced relation witheach other along a line extending between ends of said housing; saidplurality of plates having a center slot and being positioned above andadjacent to cooperable contacts of a circuit interrupter; a bafile plateimmediately above said plurality of arc plates and extending in adirection perpendicular thereto; said insulating housing containing amixing chamber above said arc plates and being partially defined by saidbafile; a passage within and at one end of said housing extending fromsaid cooperable contacts directly to said mixing chamber; said passageby-passing said balfie plate and being defined on one side by an end areplate and on the other side by said insulating housing; said passagebeing adapted to guide substantially greater quantities of gas into saidmixing chamber than each of the spaces between adjacent arc plates, aplurality of discharge passages leading from said mixing chamber to anarea external of said insulating housing at a side thereof, saidpassages having a length substantially longer than the distance betweentheir respective input ends at said mixing chamber and their respectiveoutput ends externally of said insulating housing.

4. An arc extinguisher comprising an insulating housing and a pluralityof arc plates positioned within said housing in spaced relation witheach other along a line extending between ends of said housing; saidplurality of plates having a center slot and being positioned above andadjacent to cooperable contacts of a circuit interrupter; a bafiie plateimmediately above said plurality of arc plates and extending in adirection perpendicular thereto; said insulating housing containing amixing chamber above said are plates and being partially defined by saidbaffle; a passage within and at one end of said housing extending fromsaid cooperable contacts directly to said mixing chamber; said passageby-passing said bafile plate and being defined on one side by an end areplate and on the other side by said insulating housing; said passagebeing adapted to guide substantially greater quantities of gas into saidmixing chamber than each of the spaces between adjacent arc plates, somegases generated by the are drawn by the separation of the cooperablecontacts reaching said mixing chamber by passing through said spaced arcplates, other gases generated by the are drawn by the separation of thecooperable contacts reaching said mixing chamber by passing through saidpassage; said gases passing through said passage resulting in a largedegree of turbulence in said mixing chamber to thereby aid in thede-ionization of the gases; a vent from said mixing chamber to the areasurrounding said are extinguisher at a side of said housing said venthaving a serpentine shape.

5. An arc extinguisher comprising an insulating housing and a pluralityof arc plates positioned within said housing in spaced relation witheach other along a line extending between ends of said housing; saidplurality of plates having a center slot and being positioned above andadjacent to cooperable contacts of a circuit interrupter; said areplates being positioned transverse to the are drawn between thecooperable contacts; a battle plate immediately above said plurality ofarc plates extending in a direction perpendicular thereto; saidinsulating housing having a mixing chamber located above said bafileplate; said baflle plate having a plurality of openings communicatingwith said mixing chamber to thereby provide a path for are gases createdby separation of the cooperable contacts through the spaced arc platesinto said mixing chamber; a passage Within and at one end of saidhousing extending from the cooperable contacts directly to said mixingchamber; arc gases created by the separation of said cooperable contactspassing through said passage to said mixing chamber without passingthrough the openings in said baifle plate; said passage being adapted toguide substantially greater quantities of gas into said mixing chamberthan each of the spaces between adjacent arc plates, some gasesgenera-ted by the are drawn by the separation of the cooperable contactsreaching said mixing chamber by passing through said spaced arc plates,other gases generated by the are drawn by the separation of thecooperable contacts reaching said mixing chamber by passing through saidpassage; said gases passing through said passage resulting in a largedegree of turbulence in said mixing chamber to thereby aid in thede-ionization of the gases; a vent from said mixing chamber to the areasurrounding said are extinguisher at a side of said housing; said venthaving a serpentine shape.

6. An arc extinguisher comprising an insulating housing and a pluralityof arc plates; said plurality of ar plates supported within said housingand being positioned in spaced relation with each other along a lineextending between ends of said housing; each of said plurality of arcplates having a center slot and being positioned above and adjacentcooperable contacts of a circuit breaker; said insulating housingcontaining a mixing chamber immediately above said plurality of arcplates; a passage within said housing and located at one end thereofcommunicating at one end with said cooperable contacts and the other endwith said mixing chamber; said passage being adapted to guidesubstantially greater quantities of gas into said mixing chamber thaneach of the spaces between adjacent arc plates, a discharge passageleading from said mixing chamber to an area external of said insulatinghousing at a side thereof; said passage having a length substantiallylonger than the distance between its input end at said mixing chamberand its output end externally of said insulating housing; said passagefrom 2w ,1 said housing to said mixing chamber being positioned at oneend of said housing.

7. An are extinguisher comprising an insulating housing and a pluralityof arc plates; said plurality of arc plates supported within saidhousing and being positioned in spaced relation with each other along aline extending between ends of said housing; each of said plurality ofare plates having a center slot and being positioned above and adjacentcooperable contacts of a circuit breaker; said insulating housingcontaining a mixing chamber immediately above said plurality of arcplates; a passage within said housing and located at one end thereofcommunicating at one end with said cooperable contacts and the other endwith said mixing chamber; said passage being adapted to guidesubstantially greater quantities of gas into said mixing chamber thaneach of the spaces between adjacent are plates, a discharge passageleading from said mixing chamber to an area external of said insulatinghousing; said passage having a length substantially longer than thedistance between its input end at said mixing chamber and its output endexternally of said insulating housing at a side thereof; said passagefrom said housing to said mixing being positioned at one end of saidhousing and being defined on at least one side by an arc runnerextending into said housing.

8. An arc extinguisher comprising an insulating housing and a pluralityof arc plates positioned within said housing; said plurality of plateshaving a center slot and being positioned in spaced relation above andadjacent to cooperable contacts of a circuit interrupter; a bafiie plateimmediately above said plurality of arc plates and extending in adirection perpendicular thereto; said insulating housing containing amixing chamber above said are plates and being partially defined by saidbafiie; a passage within and at one end of said housing extending fromsaid cooperable contacts directly to said mixing chamber; said passageby-passing said baffie plate and being defined on one side by an end areplate and on the other side by said insulating housing; said passagebeing adapted to guide substantially greater quantities of gas into saidmixing chamber than each of the spaces between adjacent arc plates,barrier means having openings, disposed within said chamber andpositioned transverse to said baffle plate thereby dividing said mixingchamher into a plurality of sections; a discharge passage leading fromsaid mixing chamber to an area external of said housing; said passagehaving a length substantially longer than the distance between its inputend at said mixing chamber and its output end externally of saidhousing.

9. An arc extinguisher comprising an insulating housing and a pluralityof are plates positioned within sai housing; said plurality of plateshaving a center slot and being positioned in spaced relation above andadjacent to cooperable contacts of a circuit interrupter; a bafiie plateimmediately above said plurality of arc plates and extending in adirection perpendicular thereto; said insulating housing containing amixing chamber above said are plates and being partially defined by saidbafiie, a passage within and at one end of said housing extending fromsaid cooperable contacts directly to said mixing chamber; said passageby-passing said bafile plate and being defined on one side by an end areplate and on the other side by said insulating housing; said passagebeing adapted to guide substantially greater quantities of gas into saidmixing chamber than each of the spaces between adjacent are plates,barrier means having openings, disposed within said chamber andpositioned transverse to said bafiie plate thereby dividing said mixingchamber into a plurality of sections; a discharge passage leading fromsaid mixing chamber to an area external of said housing; said passagehaving a length substantially longer than the distance between its inputend at said mixing chamber and its output end externally of saidhousing; said output end of said discharge passage positioned at a sideof said housing.

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